1 877.] 
Recent Advances in Telegraphy . 
355 
and the current admitted into the line ; next, the line or 
wire stretching from the Station A, where the message is 
sent off to the Station B, where it is received ; and next, 
the receiving instrument at Station B, actuated by the cur- 
rent from the line, so as to give sensible signals. These 
parts of the circuit are all connedfed together, and at 
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Station A one <£ pole ” of the sending battery is put in con- 
nection with the ground by means of an “ earth-plate,” 
which is generally an unoxidisable metal, such as copper ; 
while at Station B one “ terminal ” of the receiving instru- 
ment is connected, similarly, to an “ earth-plate ” there. 
A complete external circuit for the sending battery is thus 
formed through the line, the receiving instrument, and the 
2 b 2 
